﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Script.Serialization;
using System.Text;
using System.Text.RegularExpressions;
using System.Net;
using System.Globalization;
using System.Security.Cryptography;

namespace WeBlog {
	public static class Utils {
		public static double CalculateRating(int raters, double rating, double newRating) {
			double calcRating = ((rating * raters) + newRating) / (raters + 1);
			calcRating = Math.Floor((calcRating * 2) + .5) / 2;
			return calcRating;
		}

		public static string GetMD5Hash(string input) {
            if (String.IsNullOrWhiteSpace(input))
                return String.Empty;

			// step 1, calculate MD5 hash from input
			MD5 md5 = System.Security.Cryptography.MD5.Create();
			byte[] inputBytes = System.Text.Encoding.ASCII.GetBytes(input);
			byte[] hash = md5.ComputeHash(inputBytes);

			// step 2, convert byte array to hex string
			StringBuilder sb = new StringBuilder();
			for (int i = 0; i < hash.Length; i++) {
				sb.Append(hash[i].ToString("x2"));
			}
			return sb.ToString();
		}

		public static string GetSummary(string html, int length ) {
			string text = Utils.StripHtml(html);
			if (text.Length > length) {
				text = text.Substring(0, length) + " ...";
				text = "\"" + text.Trim() + "\"";
			}
			return text;
		}

		public static string GetSHA256Hash(string input) {
			byte[] data = Encoding.UTF8.GetBytes(input);
			using (HashAlgorithm sha = new SHA256Managed()) {
				byte[] encryptedBytes = sha.TransformFinalBlock(data, 0, data.Length);
				return Convert.ToBase64String(sha.Hash);
			}
		}

		public static string RemoveIllegalCharacters(string text) {
			if (string.IsNullOrEmpty(text))
				return text;

			text = text.Replace(":", string.Empty);
			text = text.Replace("/", string.Empty);
			text = text.Replace("?", string.Empty);
			text = text.Replace("#", string.Empty);
			text = text.Replace("[", string.Empty);
			text = text.Replace("]", string.Empty);
			text = text.Replace("@", string.Empty);
			text = text.Replace("*", string.Empty);
			text = text.Replace(".", string.Empty);
			text = text.Replace(",", string.Empty);
			text = text.Replace("\"", string.Empty);
			text = text.Replace("&", string.Empty);
			text = text.Replace("'", string.Empty);
			text = text.Replace(" ", "-");
			text = RemoveDiacritics(text);
			text = RemoveExtraHyphen(text);

			return HttpUtility.UrlEncode(text).Replace("%", string.Empty);
		}

		private static string RemoveExtraHyphen(string text) {
			if (text.Contains("--")) {
				text = text.Replace("--", "-");
				return RemoveExtraHyphen(text);
			}

			return text;
		}

		private static String RemoveDiacritics(string text) {
			String normalized = text.Normalize(NormalizationForm.FormD);
			StringBuilder sb = new StringBuilder();

			for (int i = 0; i < normalized.Length; i++) {
				Char c = normalized[i];
				if (CharUnicodeInfo.GetUnicodeCategory(c) != UnicodeCategory.NonSpacingMark)
					sb.Append(c);
			}

			return sb.ToString();
		}

		private static Regex _Regex = new Regex("<[^>]*>", RegexOptions.Compiled);
		/// <summary>
		/// Removes all HTML tags from a given string
		/// </summary>
		public static string StripHtml(string html) {
			if (string.IsNullOrEmpty(html))
				return string.Empty;

			return _Regex.Replace(html, string.Empty);
		}

        public static event EventHandler<EventArgs> OnLog;
        public static void Log(object message)
        {
            if (OnLog != null)
            {
                OnLog(message, new EventArgs());
            }
        }

        public static void Log(string methodName, Exception ex)
        {
            Log(String.Format("{0}: {1}", methodName, ex.Message));
        }
	}
}